I'm currently working on my tax prep for the accountant. We got a few loan top-ups against our PPR to use for one of our development projects, so the top up funds were drip-fed out of the offset account over a 12 month period. At the time it wasn't possible to have the top up funds as a separate split, which would've made life much easier. How do I calculate the interest paid on that amount? Do I need to calculate as a daily amount based on the interest rate at that date or is there an easier way and I'm overthinking it?